Apparatus responsive to phase rotation



g- 24, 1954 J. H. MILLER ETAL 2,687,512

APPARATUS RESPONSIVE TO PHASE ROTATION Filed Aug. 4, 1953 JOHN H. MILLER .400 j ROSWELL n: GILBERT INVENTORS Patented Aug. 24, 1954 UNITED STATES. PATENT OFFICE APPARATUS RESPONSIVE T PHASE ROTATION John H. Miller, Short Hills, and Roswell W. Gilbert, Montclair, N. J., as

signors to Weston Electrical Instrument Corporation, Newark, N. J a corporation of New Jersey Application August 4, 1953, Serial No. 372,275

4 Claims.

This invention relates to apparatus responsive to phase rotation and more particularly to a device of this type employing a novel arrangement of resistors, condensers and rectifiers, whereby D. C. energy is available to operate electrical devices in a sense depending upon the phase rotation of a polyphase system.

Apparatus Responsive to Phase Rotation.

Phase rotation indicators are employed to load, etc.

In general, phase rotation indicators comprise rotatable aluminum disc driven by three shad- An object of this a phase-responsive invention is the with reversal of phase.

An object of this invention is the provision of a phase rotation indicator comprising a rectifier bridge, three terminals for connection to a threephase system, a branch connection between one terminal and opposed junctions of the bridge and including a reactive component in each of the branches, resistive components connected between the other terminals and the other opposed junctions of the bridge, and a D. C. indicating instrument connected across opposed bridge junctions.

reactive component connected across these two terminals, a pair of reactive components connected between the third terminal and the other opposed junctions of the bridge, and a direct-current-responsive device connected across the latter opposed junctions of the bridge.

An object of this invention is the provision of a device responsive to the phase rotation of a three phase system and comprising a rectifier bridge, three terminals for connection to a polyphase system, individual resistors connected between two such terminals bridge junctions.

These and other objects and advantages will be apparent from the following description when taken with the accompanying drawings illustrating several embodiments of the invention. The drawings are for purposes of illustration and are not to be construed as defining the scope or limits of the invention, reference being had for the latter purpose to the appended claims.

In the drawings wherein like reference characters denote like parts in the several views:

Figure 1 is a circuit diagram illustrating a phase rotation indicator made in accordance with this invention, and employing a D. C. indicating instrument;

Figure 2 is a strument; and

Figure 3 is a circuit diagram illustrating a polarized relay responsive to the output of the modulator bridge.

Referring now to Figure 1, our device comprises a three terminal arrangement such terminals front view of the indicating inbeing identified by the numerals I, 2 and 3, and to which the three lines of a three phase system are connected when the device is placed into use. The rectifier bridge I is made up of four asymmetrical .conductors, such as coppereoxide. rectifiers, arranged in series with their direction of rectification continuous around the ring, as in a ring modulator and as shown. such a rectifier bridge provides a D. C. output across two opposed junctions, saidloutput'being.

the A. C. inputs applied across bridge junctions.-

proportional to opposed pairs of It is known that Also, the

bridge is phase-sensitive providinga D. cuoutputi having a polarity dependent luponithe phase relationship of the A. C. input waves. the drawing the terminals 2 and 3 are connected As shown in to opposed bridge junctions through the resistors H and I2, respectively, other through the condenser is. The latter is not functionally. necessary for. operation of the circuit butwithout such condenser the device will.

bridge shows that the deflection of the indicating instrument is a function otthe phase and the.

magnitude of. the-two current components that are impressed across the diagonals of the bridge. The analysis is complex andis not presented here asthe general operationof such modulator bridge isknown to those familiar .withthis art. Itmay bestated that the direct current flow in the measuring circuit would beproportionalto the prod.-

ucts of the alternating components in the-modu latorxbridgeif the rectifier elements operated. on a .pure. square law characteristic.

and the instrument approaches a linear. relation deflection is,-

exact;magnitudeof the instrument deflection or the relationship between the instrument and alternating current components is not particu-l the essential requirement is.

larlyyimportant as thatthe instrument provide. substantial deflections to opposite sides potentialsimpressed across The-specific value of the resistors l l, l2 and condensers l4, i5, is determinedby the voltage and frequency of the-three. phase system and the. char.- acteristicsof the particularindicating instrument.

In. one practical embodiment. of the invention the indicating instrument it was a zero-center milliammeter having. a scale range of 1-0-1 mawith a resistance of-somewhat less thanlOO ohms. For

the: statedvalues. 1 From the "standpoint of proper:

terminal. I through the con- Connected across these same.

responsive to thepolarity, and magnitudeof thecurrent flowing in However, the. rectifiercharacteristics are such that the response.

therefore, not strictly proportional. totheprOductbut to some'smaller. value. .The-

of the zero center position. to indicate-the phase-relationship between the the bridge diagonals.-

52.- were 62,000

!3 was 0.25 mi. With this art-- and are connectedzto each operation the condensers l4 and I5 should have an impedance, at the system frequency, of to 2 times that of the resistors H and I2, while the condenser l3 should have an impedance of less than that ofsuch resistors.

When the order of succession of the E. M. F. waves is 1-2-3 the pointer of the indicating instrument l6 will assume a position to the right of the center position on the scale, whereas upon a phase rotationof 3-2-1 the pointer will assume a position to the left of such position. It will be apparent that. the scale of the instrument may carry appropriate markings for conveying the actualphase rotation sequence to the observer, as-shown in Figure 2. If the line to terminal #l becomes disconnected the instrument will indicate zero, that is, the center scale position. If either phase 2 or 3 is lost the instrument will indicate approximately 3% of the normal deflection, the actual amount of such indication dependingiuponthevalue of the condenser 63' and if this condenser is made larger then suchdeiiece tion of the instrument pointer is further reduced. As stated hereinabove, the condenser 13 is not functionally necessary but its omission will cause the instrument pointer tov deflectslightly from.

the zero position when one of the phases becomes disconnected, thereby creating a condition of.un-.

certainty unless the scale plate of the instrument:

is marked in zones of appropriate character;

It may here be pointed out that the modulator bridge, condensers and resistors are quite small andmay conveniently be mounted: in the case of the indicating havinga conventional pointer. maybe made to harmonize with other instruments .on a switch.v the instrument and the.

board; Alternatively, associated components disposed therein maybe of the conventional, portable type;

While'our invention results in a compact phase rotation indicator of positive operation itiis not limited to such application. The the modulator bridge may be utilized. for the direct operation of nating devices.

As shown in Figure 3 putis fed to a polarized relay .20. having .a movable contact, 2! and stationary contacts maybe connected tothefilament' lamps 25, 26 having return leads connected. as shown... In this. arrangement, a phase rotation sequence. of. 1-2e3 will resultlin a closure of the relay contacts I the lamp 25. A reversal of the phase sequence to 3-2-1 results in a reversal to the otherside of the .battery,

2 I, 22,-thereby energizing of the. polarityof. the. bridge output causing the relay contacts2l, 23. to close, thereby energizing.

the lamp-.26... These lamps maybe disposed-within the instrument case in back of suitable windows marked in terms of phase rotation. Illumination of one or the other of the lamps maybe-observed from. a distance to ascertain the phase rotation.

Having described an arrangement whereby a. significant quantity of D. C. energy of reversible.

polarityis made availablein response to a reversal of phase rotation, those skilled in this art will have no difiic'ulty in developing other specific applications'of the invention. For" example; it is apparent the polarized relay shown in Figure 3 can be arranged to actuate a circuit breakerto prevent apparatus from rectly to a polyphase line.

Having now A described our 1. invention in detail instrument Such' instrument.

D. C. .output of otherDI .C.' polarity-discrimie 1 the modulator bridge outthe stationary contacts 22,:

23. The movable contact 2 I. may-beconnected to.- a source of power such as the battery 24 andthe.v

being connected incorthereby departing from the spirit and scope of the invention as set forth in the following claims.

terminal, each said condenser having an impedance at the given frequency of to 2 times that of the individual said resistors; and polarity-discriminating means connected across the said other opposed bridge junctions.

2. The invention as recited in claim 1, wherein the polarity-discriminating means is an indicating instrument having a pointer cooperating with a scale and a movable coil connected across the said other opposed bridge junctions.

3. The invention as recited in claim 2 including a condenser connected across the said first and second terminals said condenser having an 6 impedance at the given frequency of less than /2 that of both said resistors.

4. A device for indicating the relative phase rotation sequence of a three wire polyphase system having a given frequency and substantially equal voltages between wires, said device comprising three terminals for individual connection to the three wires of the polyphase system; a continuous third terminal, each said condenser having an impedance at the given frequency of to 2 times individual said resistors; an indicatsaid instrument including a pointer cooperating with a scale marked 3-2-1 and 1-2-3 to either side of center; and a condenser connected across the said first and second terminals said condenser having an impedance at the given frequency of less than that of both said resistors.

References Cited in the file of this patent UNITED STATES PATENTS ame Date Number N Keitley Sept. 5, 1950 

